This proposal is for a Clinical Trial Planning Grant to develop a protocol and manual of operations for a randomized, controlled clinical trial comparing the efficacy of combining interferonbeta (IFN) with glatiramer acetate (GA) to treat relapsing forms of multiple sclerosis (MS). At present, both IFN and GA are available, individually, for treatment of relapsing forms of MS. Pivotal trials combining agents have not yet been performed, although this approach would offer the hope of improving upon the modest efficacy results obtained in clinical trials of the agents individually. Further, there are no properly randomized, Controlled studies comparing the efficacy of IIFN to GA. The planned trial will allow for a comparison of the relative efficacy of each agent alone and in combination against the pooled results of single agent therapy or the better of the single agents. As these are expensive therapies and the results with the agents alone are modest, it is of great importance to develop better therapeutic modalities. There are currently no new agents in phase III testing for relapsing MS; thus, combination therapy is the best hope of improving treatment options for patients with relapsing MS.